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Background: Dual‐energy (DE)‐CBCT represents a promising imaging modality that can produce virtual monoenergetic (VM) CBCT images. VM images, which provide enhanced contrast and reduced imaging artifacts, can be used to assist in soft‐tissue visualization during image‐guided radiotherapy. Purpose: This work reports the development of TIGRE‐DE, a module in the open‐source TIGRE toolkit for the performance of DE‐CBCT and the production of VM CBCT images. This module is created to make DE‐CBCT tools accessible in a wider range of clinical and research settings. Methods: We developed an add‐on (TIGRE‐DE) to the TIGRE toolkit that performs DE material decomposition. To verify its performance, sequential CBCT scans at 80 and 140 kV of a Catphan 604 phantom were decomposed into equivalent thicknesses of aluminum (Al) and polymethyl‐methylacrylate (PMMA) basis materials. These basis material projections were used to synthesize VM projections for a range of x‐ray energies, which were then reconstructed using the Feldkamp‐Davis‐Kress (FDK) algorithm. Image quality was assessed by computing Hounsfield units (HU) and contrast‐to‐noise ratios (CNR) for the material inserts of the phantom and comparing with the constituent 80 and 140 kV images. Results: All VM images generated using TIGRE‐DE showed good general agreement with the theoretical HU values of the material inserts of the phantom. Apart from the highest‐density inserts imaged at the extremes of the energy range, the measured HU values agree with theoretical HUs within the clinical tolerance of ±50 HU. CNR measurements for the various inserts showed that, of the energies selected, 60 keV provided the highest CNR values. Moreover, 60 keV VM images showed average CNR enhancements of 63% and 66% compared to the 80 and 140 kV full‐fan protocols. Conclusions: TIGRE‐DE successfully implements DE‐CBCT material decomposition and VM image creation in an accessible, open‐source platform. [ABSTRACT FROM AUTHOR]

Welfare economics must adapt to the growing consensus over the assignment of rights to animals. We extend nonmarket valuation techniques to the study and measurement of the preferences of Chinook salmon regarding their aquatic habitat and the value of their existence. We find that these techniques are as valid for fish as they are for humans. Our applied study indicates that opportunities exist for Pareto-improving trades between salmon and California agricultural and hydropower interests. (JEL Q510), I. INTRODUCTION In an important book, Roderick Nash (1989) places the development of environmental ethics into the broader framework of the expansion of rights. He argues that the extension of [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2005.09.012 Byline: Yassert Gonzalez-Alvarez (a), Andrew G. Keeler (b), Jeffrey D. Mullen (c) Keywords: Water; Irrigation; Economics; Groundwater Abstract: We create a proxy for the cost of irrigation water in Georgia from a sample of Georgia irrigators by investigating the marginal cost of pumping groundwater. We then combine this proxy with agronomic and climatic variables to estimate the response of agricultural water use to differences in the marginal cost of irrigation. The results show that pumping costs are a significant determinant of water use, and imply that agricultural water use would be moderately affected by institutional changes that would explicitly price water. Author Affiliation: (a) Planning Department, Southwest Florida Water Management District, Brooksville, FL, USA (b) School of Public Policy and Management, The Ohio State University, 310-C Page Hall, 1810 College Road, The Ohio State University, Columbus, OH 43210, USA (c) Department of Agricultural and Applied Economics, The University of Georgia, Athens, GA, USA Article History: Received 17 December 2004; Revised 29 August 2005; Accepted 21 September 2005

Emissions trading markets have been successful in addressing pollution problems where regulated entities can be treated in a similar manner and precise control of emissions quantities across time and space is not critical. In other situations, trading must account for individual circumstances, complexity, and the patchwork of existing regulations. In these circumstances trading systems have elements of contracts, in that transactions are unique and must be negotiated and approved individually. Such programs imply a high payoff to improved environmental information and to innovations in trading systems that allow making better use of such information. (JEL Q21, Q25, Q28), I. INTRODUCTION Emissions trading programs have been riding a wave of ascendancy in environmental policy since the Clean Air Act Amendments of 1990 created the Acid Rain Trading Program. This [...]

A study was conducted to determine if exposure of minorities to environmentally unsafe toxic releases constitutes aversive racism. An empirical investigation of the association between race and exposure for Census block groups in George and Ohio revealed that the role of race is influenced by the breadth of the explanatory model used in the analysis. Implications for environmental policymaking are discussed.

Simulation results based on a model of landfill costs express certain reservations with the currently held belief that disposing larger volumes of wastes in regional landfills is cost effective. By considering factors such as construction, operating, externality and political costs, the model reveals that the advantages of a larger consignment is offset by the increase in transportation charges and political costs of existing zonal facilities. Intended host facilities may encounter problems from regional partners.

Three competing local options are examined by developing a model of municipal choice of solid waste disposal technologies. The three options include incineration in energy recovery facilities (ERF), landfilling and recycling. It is shown that incineration and the ERF optimum depend on the underlying costs of the different disposal options and the characteristics of the waste stream.

An enforcement model was developed wherein non-compliance penalties are determined by the strategic interaction between regulatory agencies and industries. The balance between monitoring and sanctioning activities is highly dependent on the power of the regulator's enforcement technology. This power reflects the political, legal and social opinions toward the issues being enforced. The model proves that grave offenses will be characterized by low detection rates and strong enforcement while pollution will be characterized by frequent interaction with regulators and relatively mild enforcement activity.

In this paper we develop a model to simulate the impacts of changes in freshwater flows into and out of the San Francisco Bay/Delta on the California Central Valley salmon fishery. The model also describes interactions among these water flow controls, hatchery operations, and harvest regulation. Traditionally, the management of California's freshwater resources and anadromous fisheries has been undertaken separately, in the literature and in practice. We demonstrate the potential gains from a coordinated management approach.

Shoreline armoring is a pervasive driver of habitat loss and ecosystem decline along coastlines. Nature‐based strategies for coastal protection, such as "living shorelines," offer potential alternatives to armoring and are rapidly gaining traction among conservation scientists and practitioners. However, along residential coasts where armoring has often occurred at high rates, transitioning away from armoring has been generally slow. We studied the attitudes, beliefs, and decisions of waterfront homeowners with a goal of identifying effective incentives for living shorelines as a conservation tool for reversing coastal habitat loss. We show that while only 18% of homeowners with armored shorelines would willingly transition to living shorelines during a key window of opportunity, a modest economic incentive could increase the likelihood among 43% of all respondents and up to 61% of recent homeowners. Our study demonstrates potential pathways for navigating social, economic, and environmental influences on landowner decisions for coastal habitat conservation. [ABSTRACT FROM AUTHOR]

Radiation damping is a phenomenon in which transverse nuclear magnetization couples with the current in a coil used in nuclear magnetic resonance experiments. This results in an additional magnetic field that increases the relaxation pathway for the magnetization, which then relaxes back to equilibrium more quickly. Radiation damping has been shown to affect longitudinal relaxation time (T1) measurement in inversion recovery experiments. In this work, we demonstrate that the extent of radiation damping depends upon theT1of the sample. Radiation damping difference spectroscopy is used to characterize the severity of radiation damping, while gradient inversion recovery is used for radiation damping suppression inT1measurements. At field strength of 9.4 T, for the radiation damping characteristic time (Trd) of 50 ms, these investigations show non-negligible radiation damping effects forT1values greater thanTrd, with severe distortions forT1longer than about 150 ms, showing reasonable agreement with the predictedTrd. We also report a discrepancy between published expressions for the characteristic radiation damping time. [ABSTRACT FROM AUTHOR]

The welfare effects of public versus private waste disposal with and without flow controls are analyzed. The pricing of private waste disposal services is modeled as being bounded above by the public entity's average disposal cost, but constrained by potential entry of private competitors. It is found that once a publicly owned disposal facility has been built, waste generators are almost always better off if their local government has flow control authority. This results from the necessity of covering the fixed costs of the public facility once it has been built, in conjunction with the expected pricing behavior of private firms.

Barring an unprecedented large-scale effort to raise island elevation, barrier-island communities common along the US East Coast are likely to eventually face inundation of the existing built environment on a timescale that depends on uncertain climatic forcing. Between the present and when a combination of sea-level rise and erosion renders these areas uninhabitable, communities must choose levels of defensive expenditures to reduce risks and individual residents must assess whether and when risk levels are unacceptably high to justify investment in housing. We model the dynamics of coastal adaptation as the interplay of underlying climatic risks, collective actions to mitigate those risks, and individual risk assessments based on beliefs in model predictions and processing of past climate events. Efforts linking physical and behavioural models to explore shoreline dynamics have not yet brought together this set of essential factors. We couple a barrier-island model with an agent-based model of real-estate markets to show that, relative to people with low belief in model predictions about climate change, informed property owners invest heavily in defensive expenditures in the near term and then abandon coastal real estate at some critical risk threshold that presages a period of significant price volatility. [ABSTRACT FROM AUTHOR]

Valuation of ecosystem services can provide evidence of the importance of sustaining and enhancing those resources and the ecosystems that provide them. Long appreciated only as a commercial source of oysters, oyster reefs are now acknowledged for the other services they provide, such as enhancing water quality and stabilizing shorelines. We develop a framework to assess the value of these services. We conservatively estimate that the economic value of oyster reef services, excluding oyster harvesting, is between $5500 and $99,000 per hectare per year and that reefs recover their median restoration costs in 2-14 years. In contrast, when oyster reefs are subjected to destructive oyster harvesting, they do not recover the costs of restoration. Shoreline stabilization is the most valuable potential service, although this value varies greatly by reef location. Quantifying the economic values of ecosystem services provides guidance about when oyster reef restoration is a good use of funds. [ABSTRACT FROM AUTHOR]

Fifty-five percent of Georgia's developed coastline has been armored with various types of erosion protection devices. This article is about beach improvement projects at Jekyll Island that would operate under (a) a nourishment policy or (b) a retreat policy. Benefits are calculated from an intensive, on-site survey of beach visitors and the costs are calculated from observable sources. Two financing methods are considered: general revenue and user fee financing. The analyses imply recommending beach improvement as an effective policy within the considered time frame. [ABSTRACT FROM AUTHOR]

Coastal communities exist on the front lines of diverse natural hazards and the growing impacts of climate change. While traditional strategies for dealing with coastal hazards have often involved the hardening or armoring of shorelines, more recent research and practice have demonstrated the value and cost-effectiveness of "living shorelines" and other ecosystem-based strategies for coastal protection. To explore potential relationships among geographic exposure (waterfront vs. inland), shoreline condition (armored vs. natural), and hazard concerns, we surveyed 583 waterfront and inland residents in the northern Gulf of Mexico. We found that overall concern for coastal hazards was similar across waterfront and inland residents, as well as among residents with both armored and natural shorelines. However, concern for specific hazards differed across these groups. Waterfront residents were significantly more concerned about major hurricanes and erosion than inland residents. Conversely, inland residents were more concerned with drought and flooding than waterfront residents. Among waterfront residents, specific hazard concerns were similar between residents with natural and armored shorelines with two key exceptions. Residents with armored shorelines reported higher concern for erosion and sea level rise than residents with natural shorelines. Our results suggest that armored shorelines do not necessarily alleviate concerns about coastal hazards. In the context of balancing social and ecological objectives in addressing coastal hazards or adapting to climate change, understanding the perceptions and behaviors of coastal residents is essential for conserving and protecting coastal ecosystems along residential shorelines. [ABSTRACT FROM AUTHOR]